Export 930 results:
Sort by: Author Title Type [ Year  (Desc)]
2012
Kuckova, S, et al.  2012.  Protein identification and localization using mass spectrometry and staining tests in cross-sections of polychrome samples. Journal of Cultural Heritage. AbstractWebsite

The identification and localization of the proteinaceous binders are essential issues in studies of painting materials and techniques, for further proposing valid restoration and conservation treatments of the painted or polychrome works of art. The challenge for analytical chemists and conservation scientists is the availability of methods able to simultaneously identify and map the presence of the binders in the multilayered structure of a sample and the possibility to use a very low amount of sample from the studied art object (considering also the criteria of minimum sampling). These methods should be fast, reproducible in different artefacts and in case of mixture of protein-based binders with other non-proteinaceous constituents (oils, resins, waxes, gums etc.) and also economical (both in terms of materials and time consume). In this context, the present paper proposes an innovative protocol of investigation using two complementary techniques – Matrix-Assisted Laser Desorption/Ionisation – Time of Flight Mass Spectrometry (MALDI-TOF MS) and staining tests (one visible and one fluorescent stain) assisted by Optical Microscopy (OM) on cross-section of samples – for the simultaneous identification and mapping of protein – and oil-based binders in paint materials. The novelty is based on the use of MALDI-TOF MS on cross-sections of paints together with a fluorescent stain for protein identification and mapping (mainly used in the area of proteomics) complementing the use of a traditional visible stain for oil-based material identification. The protocol was successfully applied on several samples taken from a Czech medieval polychrome sculpture, entitled “The Mourning of Jesus Christ” (16th century) belonging to the Moravian Gallery (Brno).

Ramos, S, Moura JJG, Aureliano M.  2012.  Recent advances into vanadyl, vanadate and decavanadate interactions with actin. Metallomics. 4(1):16-22., Number 1: The Royal Society of Chemistry
Neves, N, Barros R, Antunes E, Ferreira I, Calado J, Fortunato E, Martins R.  2012.  Sintering Behavior of Nano- and Micro-Sized ZnO Powder Targets for rf Magnetron Sputtering Applications. J. Am. Ceram. Soc.. 95:204-210.
Amado, M, Sousa JSão.  2012.  Solar Architecture Conference. Jornal Arquitecturas. Website
Maiti, BK, Avilés T, Matzapetakis M, Moura I, Pauleta SR, Moura JJG.  2012.  Synthesis of [MoS4]2 – M (M = Cu and Cd) clusters: Potential NMR structural probes for orange protein. Eur J Inorg Chem . 2012:4159-4166.
Carvalho, T, Augusto V, Brás AR, Lourenço NMT, Afonso CAM, Barreiros S, Correia NT, Vidinha P, Cabrita EJ, Dias CJ, Dionísio M, Roling B.  2012.  Understanding the Ion Jelly Conductivity Mechanism. The Journal of Physical Chemistry B. 116(9):2664-2676.Website
Maia, MJ, Moiteiro AI, Horstink L, Farelo M, Antunes R.  2012.  {Análise de um processo decisório controverso: a co-incineração em Souselas [Analysis of a controversial decision process: the co-incineration at Souselas]}. , Number 10/2012: Universidade Nova de Lisboa, IET/CICS.NOVA-Interdisciplinary Centre on Social Sciences, Faculty of Science and Technology Abstract

The scientific controversy generated around the destiny given to the fraction of hazardous industrial waste produced in Portugal and how the country dealt with this situation was the stand out point in Souselas case. Here, the dominant aspect of the analysis focused on the implementation of a solution for the treatment of hazardous industrial waste. These wastes result from industrial processes contain or are contaminated, by substances that, at certain concentrations, represent a risk to human health or to the environment. Their treatment can be done using co-incineration in existing cement factories. Having in mind the environment analysis of a controversial process, through the statements made by the different actors involved, the case of Souselas was our object of study. Initially, the actors involved in the process were identified and characterized, in terms of position, interests and / or concerns. This analysis has strengthened with the gathering of documentary elements of analysis. In a second phase the historical process was prepared. Only then, the conditions to make an interpretation of what really happened in the process were gathered, then , it was possible to identify which parts were successful and unsuccessful, and to interpret “why” these successes and failures occurred. Thus, after the identification of key variables and leverage points, a causal diagram and a schematic simulation of the behaviour of reference in case Souselas was designed. We conclude that the process of Souselas was a significant milestone with regard to social organization and spontaneous local actors in situations of opposition to central government decisions with local impact. It was also a turning point in governance according to the model of representative democracy, whose technocratic and elitist character is called into question. The Souselas case emphasized itself as a microcosm on the conflict of interests that we find at a global level heightened since the 90s and that

Bonifacio, VDB, Correia VG, Pinho MG, Lima JC, Aguiar-Ricardo A.  2012.  Blue emission of carbamic acid oligooxazoline biotags. Materials Letters. 81:205-208. Abstract
n/a
Rodriguez, L, Ferrer M, Crehuet R, Anglada J, Lima JC.  2012.  Correlation between Photophysical Parameters and Gold-Gold Distances in Gold(I) (4-Pyridyl)ethynyl Complexes. Inorganic Chemistry. 51:7636-7641., Number 14 Abstract
n/a
Ferraz, R, Branco LC, Marrucho IM, Araujo JMM, Rebelo LPN, da Ponte MN, Prudencio C, Noronha JP, Petrovski Z.  2012.  Development of novel ionic liquids based on ampicillin. Medchemcomm. 3:494-497., Number 4 AbstractWebsite
n/a
Bras, JLA, Carvalho AL, Viegas A, Najmudin S, Alves VD, Prates JAM, Ferreira LMA, Romao MJ, Gilbert HJ, Fontes CMGA.  2012.  ESCHERICHIA COLI EXPRESSION, PURIFICATION, CRYSTALLIZATION, AND STRUCTURE DETERMINATION OF BACTERIAL COHESIN-DOCKERIN COMPLEXES. Cellulases. 510(Gilbert, H. J., Ed.).:395-415. Abstract
n/a
Antunes, R, Coito F, Duarte-Ramos H.  2012.  Improving Operator Performance through the Use of a Multivariable Human-Machine Control Strategy. Technological Innovation for Value Creation. :95–104.: Springer Boston Abstract

n/a

Bras, JLA, Alves VD, Carvalho AL, Najmudin S, Prates JAM, Ferreira LMA, Bolam DN, Romao MJ, Gilbert HJ, Fontes CMGA.  2012.  Novel Clostridium thermocellum Type I Cohesin-Dockerin Complexes Reveal a Single Binding Mode. Journal of Biological Chemistry. 287:44394-44405., Number 53 AbstractWebsite
n/a
Gago, S, Gomes AC, Cunha-Silva L, Pillinger M, Goncalves IS, Almeida Paz FA.  2012.  A novel dinuclear MoVI complex with tris(3,5-dimethyl-1H-pyrazol-1-yl)methane. Acta Crystallographica Section C-Crystal Structure Communications. 68:M73-M75. AbstractWebsite
n/a
Roldao, A, Mellado MCM, Lima JC, Carrondo MJT, Alves PM, Oliveira R.  2012.  On the Effect of Thermodynamic Equilibrium on the Assembly Efficiency of Complex Multi-Layered Virus-Like Particles (VLP): the Case of Rotavirus VLP. Plos Computational Biology. 8, Number 2 Abstract
n/a
Velasco, LF, Fonseca IM, Parra JB, Lima JC, Ania CO.  2012.  Photochemical behaviour of activated carbons under UV irradiation. Carbon. 50:249-258., Number 1 Abstract
n/a
Aveiro, SS, Freire F, Clayton J, Cameloc M, Carvalho AL, Ferreira GC, Romao MJ, Macedo AL, Goodfellow BJ.  2012.  Structural studies of the p22HBP/SOUL family of heme-binding proteins. Febs Journal. 279:458-458. AbstractWebsite
n/a
Sousa, AMM, Morais S, Abreu MH, Pereira R, Sousa-Pinto I, Cabrita EJ, Delerue-Matos C, Gonca̧lves MP.  2012.  Structural, Physical, and Chemical Modifications Induced by Microwave Heating on Native Agar-like Galactans. Jornal of Agricultural and Food Chemistry. 60:4977-4985. Abstract

Native agars from Gracilaria vermiculophylla produced in sustainable aquaculture systems (IMTA) were extracted under conventional (TWE) and microwave (MAE) heating. The optimal extracts from both processes were compared in terms of their properties. The agars’ structure was further investigated through Fourier transform infrared and NMR spectroscopy. Both samples showed a regular structure with an identical backbone, β-D-galactose (G) and 3,6-anhydro-α-L-galactose (LA) units; a considerable degree of methylation was found at C6 of the G units and, to a lesser extent, at C2 of the LA residues. The methylation degree in the G units was lower for MAEopt agar; the sulfate content was also reduced. MAE led to higher agar recoveries with drastic extraction time and solvent volume reductions. Two times lower values of [η] and Mv obtained for the MAEopt sample indicate substantial depolymerization of the polysaccharide backbone; this was reflected in its gelling properties; yet it was clearly appropriate for commercial application in soft-texture food products.

da Silva, MS, Viveiros R, Coelho MB, Aguiar-Ricardo A, Casimiro T.  2012.  Supercritical CO2-assisted preparation of a \{PMMA\} composite membrane for bisphenol A recognition in aqueous environment. Chemical Engineering Science. 68:94-100., Number 1 AbstractWebsite

This work reports a novel strategy to prepare affinity composite membranes using supercritical fluid technology. By blending molecularly imprinted polymeric particles with PMMA, a porous hybrid structure with affinity to the template molecule, bisphenol A, was prepared using a supercritical carbon dioxide (scCO2)-assisted method. Membranes were characterized in terms of morphology, mechanical performance and transport properties. The ability of the polymers and hybrid membranes to adsorb bisphenol A was tested in aqueous solutions and fitted to a linearized Langmuir equation, showing that adsorption takes place at homogeneous affinity binding sites within the imprinted surface. Filtration experiments showed that the imprinted hybrid membrane was able to adsorb higher amounts of template even in non-equilibrium dynamic binding conditions. The hybridization of the \{PMMA\} membrane herein reported conveys two important improvements over neat \{PMMA\} membrane: it introduced molecular affinity towards the template molecule and significantly increased the permeability of the porous structures, which are key parameters in processes that involve membranes. This technique could expand the applications of polymeric beads powders and enhance the efficiency of the membrane's transport properties. Our work presents a new method to confer affinity to a porous structure by immobilization of imprinted polymers, combining polymer synthesis and membrane formation using supercritical fluid technology.

da Silva, MS, Viveiros R, Aguiar-Ricardo A, Bonifacio VDB, Casimiro T.  2012.  Supercritical fluid technology as a new strategy for the development of semi-covalent molecularly imprinted materials. RSC Adv.. 2:5075-5079.: The Royal Society of Chemistry AbstractWebsite

Molecularly imprinted polymeric particles with molecular recognition towards Bisphenol A (BPA) were synthesized for the first time using the semi-covalent imprinting approach in supercritical carbon dioxide (scCO2). The material{'}s affinity to BPA was achieved by co-polymerizing ethylene glycol dimethacrylate (EGDMA) with a template-containing monomer{,} Bisphenol A dimethacrylate (BPADM) in scCO2. Bisphenol A is then cleaved from the polymeric matrix by hydrolysis with tetrabutylammonium hydroxide (n-Bu4OH) also in a supercritical environment{,} taking advantage of the high diffusivity of scCO2. The selectivity of the molecular imprinted polymer (MIP) was assessed by evaluating its capability to bind BPA in comparison with progesterone and [small alpha]-ethinylestradiol. In addition{,} the cross-linked particles were used to prepare a PMMA-based hybrid imprinted membrane by a scCO2-assisted phase inversion method. Results show that the incorporation of MIP particles was able to confer molecular affinity to BPA to the membrane and that at dynamic conditions of filtration{,} this imprinted porous structure was able to adsorb a higher amount of BPA than the corresponding non-imprinted hybrid membrane. Our work represents a valuable greener alternative to conventional methods{,} for the synthesis of affinity materials which are able to maintain molecular recognition properties in water.

Gordo, J, Máximo P{\'ıcia, Cabrita E, c}o AL{\c, Oliva A, Almeida J, Filipe M, Cruz P, Barcia R, Santos M, Cruz H.  2012.  Thymus mastichina: Chemical Constituents and their Anti-cancer Activity. Natural Product Communications. 7:1491-1494. Abstract
n/a
Carvalho, T, Augusto V, Brás AR, c}o L{\cNMT, Afonso CAM, Barreiros S, Correia NT, Vidinha P, Cabrita EJ, Dion{\'ısio M, Roling B.  2012.  Understanding the Ion Jelly Conductivity Mechanism. Journal of Physical Chemistry B. 116:2664-2676. Abstract

The properties of the light flexible device, ion jelly, which combines gelatin with an ionic liquid (IL) were recently reported being promising to develop safe and highly conductive electrolytes. This article aims for the understanding of the ion jelly conductive mechanism using dielectric relaxation spectroscopy (DRS) in the frequency range 10-1-106 Hz; the study was complemented with differential scanning calorimetry (DSC) and pulse field gradient nuclear magnetic resonance (PFG NMR) spectroscopy. The room temperature ionic liquid 1-butyl-3-methylimmidazolium dicyanamide (BMIMDCA) used as received (1.9% w/w water content) and with 6.6% (w/w) of water content and two ion jellies with two different ratios BMIMDCA/gelatin/water % (w/w), IJ1 (41.1/46.7/12.2) and IJ3 (67.8/25.6/6.6), have been characterized. A glass transition was detected by DSC for all materials allowing for classifying them as glass formers. For the ionic liquid, it was observed that the glass transition temperature decreases with the increase of water content. While in subsequent calorimetric runs crystallization was observed for BMIMDCA with negligible water content, no crystallization was detected for any of the ion jelly materials upon themal cycling. To the dielectric spectra of all tested materials, both dipolar relaxation and conductivity contribute; at the lowest frequencies, electrode and interfacial polarization highly dominate. Conductivity, which manifests much more intensity relative to dipolar reorientations, strongly evidences subdiffusive ion dynamics at high frequencies. From dielectric measures, transport properties as mobility and diffusion coefficients were extracted. Data treatment was carried out in order to deconvolute the average diffusion coefficients estimated from dielectric data in its individual contributions of cations (D+) and anions (D-). The D+ values thus obtained for IJ3, the ion jelly with the highest IL/gelatin ratio, cover a large temperature range up to room temperature and revealed excellent agreement with direct measurements from PFG NMR, obeying to the same VFT equation. For BMIMDCA6.6%water, which has the same water amount as IJ3, the diffusion coefficients were only estimated from DRS measurements over a limited temperature range; however, a single VFT equation describes both DRS and PFG NMR data. Moreover, it was found that the diffusion coefficients and mobility are similar for the ionic liquid and IJ3, which points to a role of both water and gelatin weakening the contact ion pair, facilitating the translational motion of ions and promoting its dissociation; nevertheless, it is conceivable that a critical composition of gelatin that leads to those properties. The VFT temperature dependence observed for the conductivity was found to be determined by a similar dependence of the mobility. Both conductivity and segmental motion revealed to be correlated as inferred by the relatively low values of the decoupling indexes. The obtained results show that ion jelly could be in fact a very promising material to design novel electrolytes for different electrochemical devices, having a performance close to the IL but presenting an additional stability regarding electrical measurements and resistance against crystallization relative to the bulk ionic liquid.

2011
Almeida, RM, Geraldes CF, Pauleta SR, Moura JJ.  2011.  Gd(III) chelates as NMR probes of protein-protein interactions. Case study: rubredoxin and cytochrome c3, Nov 7. Inorg Chem. 50:10600-7., Number 21 AbstractWebsite

Two cyclen-derived Gd probes, [Gd-DOTAM](3+) and [Gd-DOTP](5-) (DOTAM = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetamide; DOTP = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonate)), were assessed as paramagnetic relaxation enhancement (PRE)-inducing probes for characterization of protein-protein interactions. Two proteins, Desulfovibrio gigas rubredoxin and Desulfovibrio gigas cytochrome c(3), were used as model partners. In a (1)H NMR titration it was shown that [Gd-DOTP](5-) binds to cytochrome c(3) near heme IV, causing pronounced PREs, characterized by line width broadenings of the heme methyl resonances at ratios as low as 0.08. A K(d) of 23 +/- 1 muM was calculated based on chemical shift perturbation of selected heme methyl resonances belonging to three different heme groups, caused by allosteric effects upon [Gd-DOTP](5-) binding to cytochrome c(3) at a molar ratio of 2. The other probe, [Gd-DOTAM](3+), caused PREs on a well-defined patch near the metal center of rubredoxin (especially the patch constituted by residues D19-G23 and W37-S45, which broaden beyond detection). This effect was partially reversed for some resonances (C6-Y11, in particular) when cytochrome c(3) was added to this system. Both probes were successful in causing reversible PREs at the partner binding site, thus showing to be good probes to identify partners' binding sites and since the interaction is reversible to structurally characterize protein complexes by better defining the complex interface.

Mathies, G, Blok H, Disselhorst JA, Gast P, van der Meer H, Miedema DM, Almeida RM, Moura JJ, Hagen WR, Groenen EJ.  2011.  Continuous-wave EPR at 275GHz: application to high-spin Fe(3+) systems, May. J Magn Reson. 210:126-32., Number 1 AbstractWebsite

The 275GHz electron-paramagnetic-resonance spectrometer we reported on in 2004 has been equipped with a new probe head, which contains a cavity especially designed for operation in continuous-wave mode. The sensitivity and signal stability that is achieved with this new probe head is illustrated with 275GHz continuous-wave spectra of a 1mM frozen solution of the complex Fe(III)-ethylenediamine tetra-acetic acid and of 10mM frozen solutions of the protein rubredoxin, which contains Fe(3+) in its active site, from three different organisms. The high quality of the spectra of the rubredoxins allows the determination of the zero-field-splitting parameters with an accuracy of 0.5GHz. The success of our approach results partially from the enhanced absolute sensitivity, which can be reached using a single-mode cavity. At least as important is the signal stability that we were able to achieve with the new probe head.

Fievet, A, My L, Cascales E, Ansaldi M, Pauleta SR, Moura I, Dermoun Z, Bernard CS, Dolla A, Aubert C.  2011.  The Anaerobe-Specific Orange Protein Complex of Desulfovibrio vulgaris Hildenborough Is Encoded by Two Divergent Operons Coregulated by sigma(54) and a Cognate Transcriptional Regulator, Jul. Journal of Bacteriology. 193:3207-3219., Number 13 AbstractWebsite

Analysis of sequenced bacterial genomes revealed that the genomes encode more than 30% hypothetical and conserved hypothetical proteins of unknown function. Among proteins of unknown function that are conserved in anaerobes, some might be determinants of the anaerobic way of life. This study focuses on two divergent clusters specifically found in anaerobic microorganisms and mainly composed of genes encoding conserved hypothetical proteins. We show that the two gene clusters DVU2103-DVU2104-DVU2105 (orp2) and DVU2107-DVU2108-DVU2109 (orp1) form two divergent operons transcribed by the sigma(54)-RNA polymerase. We further demonstrate that the sigma(54)-dependent transcriptional regulator DVU2106, located between orp1 and orp2, collaborates with sigma(54)-RNA polymerase to orchestrate the simultaneous expression of the divergent orp operons. DVU2106, whose structural gene is transcribed by the sigma(70)-RNA polymerase, negatively retrocontrols its own expression. By using an endogenous pulldown strategy, we identify a physiological complex composed of DVU2103, DVU2104, DVU2105, DVU2108, and DVU2109. Interestingly, inactivation of DVU2106, which is required for orp operon transcription, induces morphological defects that are likely linked to the absence of the ORP complex. A putative role of the ORP proteins in positioning the septum during cell division is discussed.

loading